• Authors:
    • Pauletti, V.
    • Favaretto, N.
    • Molin, R.
    • Mellek, J. E.
    • Dieckow, J.
    • Da-Silva, V. L.
    • Vezzani, F. M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 3
  • Year: 2012
  • Summary: The quality of no-tillage systems depends on an adequate soil management that promotes soil structure improvements. This is associated to the cropping system adopted. This study investigated the effect of long-term no-tillage systems (18 years) on the structural quality of a sandy-clay to clay Oxisol (Latossolo Vermelho) in the region of Campos Gerais, Parana, Brazil. Five cropping systems were assessed: wheat-soybean [Wt-So], black oat-maize-wheat-soybean [Ot-Mz-Wt-So], vetch-maize-wheat-soybean [Vt-Mz-Wt-So], ryegrass-maize-ryegrass-soybean [Rg-Mz-Rg-So]; and alfalfa-maize [Alf-Mz]. Soil was sampled from the layers 0-5, 5-10 and 10-20 cm, in cylinders and in blocks with undisturbed structure. In the 0-5 cm layer, bulk density was lowest in the Ot-Mz-Wt-So (0.96 Mg m -3) and Vt-Mz-Wt-So systems (0.93 Mg m -3). In the 5-10 and 10-20 cm layers, the bulk density tended to be lowest in Alf-Mz systems (1.14 and 1.17 Mg m -3, respectively). A similar trend was observed for macroporosity, which in the top layer was greater in Ot-Mz-Wt-So (0.29 m 3 m -3) and Vt-Mz-Wt-So (0.30 m 3 m -3) and in the 5-10 and 10-20 cm layers tended to be greater in the Alf-Mz system (0.19 m 3 m -3). No clear trend was observed for microporosity. The saturated hydraulic conductivity was directly related with macroporosity, and was highest for Vt-Mz-Wt-So in the 0-5 cm layer (224 mm h -1) and Alf-Mz in the layers 5-10 (170 mm h -1) and 10-20 cm (147 mm h -1). In the Vt-Mz-Wt-So system, the mean weight diameter of aggregates was lowest in the 0-5 cm layer (2.39 mm) and highest (3.04 mm) in the Wt-So. The highest cone index values were observed in the Wt-So system, with over 1.5 MPa in the 7.5-22.5 cm layer. The compaction degree was lowest in the Alf-Mz system (0.2 MPa cm). Results were attributed mainly to the role of the crop roots of the systems and to the intensity of machinery traffic. Considering the 0-20 cm layer as a whole, the capacity to promote soil structural quality improvements was greater for the semi-perennial Alf-Mz system than for systems based on annual species. Bi-annual rotation systems, based on cover crops such as black oat and vetch, promote soil structural quality improvements compared to the wheat - soybean succession.
  • Authors:
    • Oliveira, P. S. R. de
    • Costa, A. C. T. da
    • Demetrio, J. V.
  • Source: Pesquisa Agropecuaria Tropical
  • Volume: 42
  • Issue: 2
  • Year: 2012
  • Summary: In the crop-livestock integration system, improper oat management can result in low biomass yield. This study aimed to evaluate the effect of cutting management systems on the biomass yield of five oat cultivars with potential use in the crop-livestock integration system. A completely randomized blocks design with four replications, in a split-plot scheme, was used. The plots were represented by the oat cultivars Preta Comum, IAPAR 61, IPR 126, FAPA 2, and FUNDACEP FAPA 43. The Preta Comum cultivar features a short cycle, while the others have a long one. The sub-plots were represented by the following cutting systems: one single cut in the flowering stage, one cut in the vegetative and other in the flowering stage, two cuts in the vegetative and other in the flowering stage, and three cuts in the vegetative and other in the flowering stage. The long cycle cultivars (IAPAR 61, IPR 126, FAPA 2, and FUNDACEP FAPA 43) reached high forage yield, without affecting the subsequent fodder yield for soil covering, pointing out its ability to be used in crop-livestock systems. The management systems with three cuts in the vegetative stage maximizes the forage yield, however, concerning fodder yield, the best results were obtained by using up to two cuts in the vegetative stage, or a single one in the flowering stage.
  • Authors:
    • Ferrari, J. V.
    • Furlani Junior, E.
    • Ferrari, S.
    • Alberton, J. V.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 7
  • Issue: 2
  • Year: 2012
  • Summary: The fiber quality, productivity and favorable climate are considered key points for the development of the cotton crop in the Brazilian Cerrado. This study aimed to evaluate the effect of cover crops and N application in pre-sowing on the cotton crop growth and yield. The experimental design was randomized blocks, consisting of a - three cover crops (radish, white oat and black oat) implanted during the winter period, b - four nitrogen levels (0, 30, 60 and 90 kg ha -1 of N) applied to the millet residues and before cotton sowing. In April 2008, evaluations were realized of plant development and also harvesting was performed of experimental plots of cotton plants. The results showed that the radish provides increased length of branches and cotton bolls of cotton crop, without yield increase, and the use of increasing doses of N up to 90 kg ha -1 decreased the amount of carima per plant, increasing the number of reproductive branches and cotton yield.
  • Authors:
    • Rodrigues, J. G. L.
    • Fernandes, D. M.
    • Bicudo, S. J.
    • Nascimento, F. M.
    • Fernandes, J. C.
    • Furtado, M. B.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 7
  • Issue: 1
  • Year: 2012
  • Summary: The main goal of this research was to evaluate the response of maize crop in succession to maize+oat crops, with the anticipation of the increasing doses of nitrogen application in the oat culture, in no-tillage system. The experiment was carried out under field conditions at FCA/UNESP, Botucatu Campus, Sao Paulo, Brazil. The experimental design was arranged in randomized blocks with four replications, in split-plots. The plots were the nitrogen doses applied on the oat crop (0, 20, 40 e 60 kg ha -1), and split-plots, the nitrogen doses applied in the cover (60, 80, 100 e 120 kg ha -1), divided into two different crop stages of the maize crop. The dry matter weight and the C/N ratio were assessed on the oat and maize crops. On the maize crop, the plant nitrogen was quantified before the first covering and 15 days after the second covering, when the dry matter weight of the maize plants was determined. After the harvest, the yield was also calculated. Results indicate that the maize development and yield under no-till system were related to the straw C/N ratio, and the maize crop response to the anticipated N fertilization anticipation varied according to the N doses and application periods. The dry matter weight of the maize plants were influenced by the rates and periods of N applications.
  • Authors:
    • Tres, T.
    • Jobim, C.
    • Oliveira, E.
    • Oliveira, P.
    • Castagnara, D.
    • Neres, M.
    • Mesquita, E.
  • Source: REVISTA BRASILEIRA DE ZOOTECNIA-BRAZILIAN JOURNAL OF ANIMAL SCIENCE
  • Volume: 41
  • Issue: 4
  • Year: 2012
  • Summary: The experiment was carried out to evaluate the structural characteristics, biomass accumulation, chemical composition and in vitro digestibility of dry matter and crude protein of white oat ( Avena sativa L. IPR 126) under different management systems. Grazing, cut at two heights (15 and 20 cm) and free growth were all evaluated in three periods (July, August and September) with a 28-day average interval between evaluations. In the free growth system, samples at 15 and 20 cm were also taken at the intervals chosen for cutting and grazing. The experimental design was in randomized blocks with three replications, arranged in a 3*2 factorial split plot design over time; systems of management and heights were the factors of plots, and time was taken as subplot. There was higher straw production under free growth, but, with decreased chemical quality from the first to the second period and from the second to the third one, with 236.4, 172.5, and 91.4 g/kg crude protein values, respectively. Regarding cutting and grazing systems, they showed structural changes in tillering, which was favored by the cut, but with some reduction in the periods. Nutritional quality values were close to cutting and grazing with high crude protein content (216.6 g/kg), adequate neutral detergent fiber (535.4 g/kg) content and high in vitro digestibility of dry matter (826.3 g/kg). Management heights promoted few changes in the characteristics evaluated. After the third period, cutting and grazing systems showed no suitable residual straw for ground covering and set a summer crop under no-tillage system, with 738.39 kg/ha of residual dry matter on average.
  • Authors:
    • Fontoura, S. M. V.
    • Bayer, C.
    • Rojas, C. A. L.
    • Weber, M. A.
    • Vieiro, F.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 1
  • Year: 2012
  • Summary: Nitrogen losses from urea by ammonia volatilization are higher from no-tillage than from conventional tillage. The objective of this study was to evaluate the magnitude of this process under cool and wet spring conditions in the South-Central region of the State of Parana and to evaluate the influence of two winter cover crops (black oat and common vetch) on ammonia volatilization in no-tillage. The tillage systems were compared in a long-term tillage experiment (28 years) and the cover crops tested separately in a long-term (>15 yr) no-tillage area. Maize was grown in both experiments. Urea was applied at rates of 0, 80 and 160 kg ha -1 N in a single application in the tillage experiment and at rates of 0, 100 and 200 kg ha -1 N, split in two applications, in the cover crop experiment. Volatilization of NH 3 was measured for 20 days after urea application in a semi-open static system. Urease activity was evaluated in both experiments. The NH 3 loss rates were highest 5 days after urea application. Cumulative ammonia losses reached 18% of the applied N in no-tillage and 3% in conventional tillage. The higher losses from no-tillage may be partially related to the greatest urease activity in the soil surface layer. Ammonia volatilization was not affected by cover crops. As an isolated practice, split surface N fertilization does not ensure a decrease of NH 3 losses, which are primarily related to rain events immediately after urea application.
  • Authors:
    • Calegari, A.
    • Santos, D.
    • Tiecher, T.
  • Source: Soil & Tillage Research
  • Volume: 124
  • Year: 2012
  • Summary: Organic phosphorus (P) is an important source of phosphate for plants both in natural environments and in cultivated soils. Growing plants with high P recycling capacity may increase the importance of organic forms in phosphate availability mainly in undisturbed soils. The aim of this study was to evaluate the effect of long period of cultivation of different winter species under different soil management systems in the distribution of soil organic P forms, in the P content stored into the soil microbial biomass (SMB) and in the acid phosphatase enzyme activity. The experiment was established in 1986 with six winter treatments (blue lupine, hairy vetch, oat, radish, wheat and fallow) implanted in a Rhodic Hapludox in southern Brazil, under no-tillage system (NT) and conventional tillage system (CT). The crops were cultivated with rational use of chemical phosphate fertilizer, according to plant needs and soil type maintaining high levels of soil organic carbon leading to P organic form accumulation. Growing crops during the winter period in highly weathered subtropical soil increases the importance of microbial interactions in the P cycle, especially in the NT, where a large amount of crop residues is annually added to the soil surface, increasing soil organic P level, P content stored into the SMB and acid phosphatase enzyme activity.
  • Authors:
    • Baade, E.
    • Tramontin, A.
    • Sturmer, S.
    • Grossklaus, F.
    • Valicheski, R.
  • Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
  • Volume: 16
  • Issue: 9
  • Year: 2012
  • Summary: With the intense use of technologies geared toward the mechanization of agricultural operations, soil compaction is a factor limiting productivity. To mitigate this problem, the use of ground cover crops is frequently recommended. With the objective to determine the effect of compaction on the soil physical properties, an experiment was carried out using randomized block design in a 2*5 factorial scheme. Two cover crop species (black oat - Avena strigosa and forage radish - Raphanus sativus), five levels of compaction (0, 2, 4, 6 and 8 tractor passes with 5.0 Mg on the soil surface), with four repetitions were studied. Traffic intensities greater than 2 tractor passes change soil density, total porosity, and mechanical penetration resistance at a depth of 0-0,10 m, as well as linearly reduce the height and dry matter production of the above-ground parts of the cover crops. The cultivation of black oat or forage radish preceding the soybeans, associated with the use of a furrower during soybean sowing minimizes the effects of soil compaction, permitting to obtain productivity greater than 3,5 t ha -1.
  • Authors:
    • Franchini, J.
    • Jantalia, C.
    • Urquiaga, S.
    • Boddey, R.
    • Zatorre, N.
    • Zotarelli, L.
    • Alves, B.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: The sustainability of crop production systems depends on the adoption of practices that allow the balancing of nutrient output and the preservation of soil organic matter. In Brazil, no-tillage (NT) is widely adopted for soybean-based cropping systems. In the Southern region, soybean alternates with maize in the summer and black-oats or wheat in the winter. Green-manure legumes are occasionally introduced in the crop rotation to break the continuous use of wheat in the winter. The objective of the present study was to evaluate if NT adoption would increase biological nitrogen fixation to soybean and other legumes. The hypothesis that a system richer in N would bring about positive effects on soil C stocks, was also tested. The study was carried out in Londrina, Parana State, in Southern Brazil on a clayey Ferralsol that was cropped under NT with soybean as the main crop for more than 25 years. In 1997, three different crop rotations under both NT and conventional plough tillage (CT) were introduced. The crop rotations were composed of soybean, maize, wheat, black-oats and white lupins, but differed from each other in the frequency that each crop appeared in the rotation. Crop yields and the biomass of lupins and black-oats were quantified at every harvest during the 12 years of this study. Conversion factors of measured yield and biomass into C and biologically fixed N inputs to the crop system were developed from whole plant measurements performed in four of the twelve years of the study. The contribution of biological N 2 fixation (BNF) to the legumes was determined using the ureide abundance and the 15N natural abundance techniques in 1998, 1999, 2005 and 2007. From these data, the calculation of N balance for each rotation (input N minus output N in harvested grain) was carried out. Soil C and N stocks to 80 cm depth were quantified in 1997, 2003 and 2009. Grain yields were higher under NT for soybean and under CT for maize, in the rotation with the lowest frequency of legume crops. Soybean reliance on BNF was higher under NT (76%) than under CT (68%) whilst for lupins the reliance was 68% under NT and 60% under CT. The use of lupins as a green manure represented an extra contribution to soil N of approximately 300 kg N ha -1 and this was essential to maintain a positive N balance for the system. The comparison of soil C stocks between 1997 and 2009 revealed almost no gain in soil C under NT, but a C loss of 19 Mg C ha -1 after 12 years of CT. Significant soil C and N losses were recorded in the rotation where lupins were planted more frequently and fertilizer N application to maize was suspended, which resulted in a very negative N balance for the system. The results highlight the importance of NT to enhance BNF inputs to the system and the need to recognize the N balance as a key driver of C stock changes in the soil. In addition, it suggests NT in this study had the consequence of avoiding soil C loss rather than increasing soil C stocks.
  • Authors:
    • Callado, S.
    • Albino, J.
  • Source: Emirates Journal of Food and Agriculture
  • Volume: 24
  • Issue: 4
  • Year: 2012
  • Summary: The article is based on an agro-ecological evaluation of seven different agricultural systems in Teresopolis, Rio de Janeiro. The studied systems are dealing with: vegetable production system, ecological husbandry, cattle production system, sylvopastoral approaches as well as citrus cropping systems. The main objective is to evaluate the environmental impact of these systems using the "Emergy Analysis" as methodology. For this purpose, input data as materials, services, natural renewable/nonrenewable sources of 42 crops were analyzed. This method is based on energy flows, transforming all inputs and outputs in a common unit. This analysis allows comparisons across agricultural systems and their environmental impacts, as well as, makes possible the identification of scenarios to achieve greater sustainability. The main conclusions of this study are: the vegetable systems have large amounts of energy invested in irrigation, fertilizers and fuels; the largest value of sustainability corresponds to the ecological systems and it has the capacity to save capital in form of biomass in the system; cattle system causes bigger environmental damage and have the smallest yield per hectare in economic and energy terms; as for the citrus systems, a low investment rate was found and the use of renewable resources from this system is comparable to the vegetable systems.